The present invention relates to differential amplifiers in general, and in particular to a differential amplifier with active transient response correction.
In high-frequency amplifiers, it is generally desirable to have a means by which the transient response of an individual stage can be varied, primarily to compensate for variations in the active devices which occur during the manufacturing process. Typically, transient-response adjustments (also known as high-frequency compensation or signal peaking) are made by varying the values of reactive passive elements such as capacitors or inductors in the signal path. The conventional transient-response adjustment method is found to be lacking in several respects. First, reactive components (or the tools used to adjust them) often introduce parasitic reactances into the circuit which compromise performance. Second, with the advent of micro-miniaturization of amplifiers in the form of integrated circuits, the sensitive circuit nodes which require adjustment are often inaccessible. Third, reactive passive elements are often expensive, and the costs are cumulative where several amplifier stages are required. Finally, the conventional methods for transient-response adjustments do not lend themselves to automatic or programmable control, or to cases in which functional control of transient response is desirable, e.g., such as with temperature or signal strength.